scholarly journals Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sondes Bouabdallah ◽  
Med Thaieb Ben Dhia ◽  
Med Rida Driss
Keyword(s):  
Experimental Data ◽  
Thermodynamic Parameters ◽  
Conformational Equilibrium ◽  
Theoretical Calculations ◽  
Nmr Data ◽  
Major Species ◽  
B3lyp Calculations

The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is thetransform. The proportion was 77% and 23% for thetransandcis, respectively. The thermodynamic parameters (ΔH,ΔS, andΔG) were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations.

scholarly journals Uso de Cálculos de RMN de 13C e 1H e Redes Neurais no Auxilio da Determinação Estrutural da Savinina

2020 ◽  
Author(s):  
Evani Ferreira Cardoso ◽  
Rodrigo de Souza Miranda ◽  
Roberto Carlos Campos Martins ◽  
Gunar Vingre da Silva Mota ◽  
Antônio Maia de Jesus Chaves Neto ◽  
...  
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Immune System ◽  
1H Nmr ◽  
Theoretical Calculations ◽  
Human Colon ◽  
Human Colon Carcinoma ◽  
Nmr Data ◽  
The Neural Network ◽  
Hct116 Cells

This is a theoretical-experimental work, where the focus molecule of the study is savinine, a lignan of the dibenzylbutyrolactonic type, substances that can be found in several genera, one of which has a greater occurrence is the genus Acanthopanax (Araliaceae) which is traditionally used as an analgesic and immune system stimulant, in addition to exhibiting a potent insecticidal and cytotoxic activity for human colon carcinoma HCT116 cells. It was isolated and here we present its experimental and theoretical characterization by means of 13C and 1H NMR data and the possible confirmation of the structure using the neural network tool (ANN-PRA). The objective of this work is to use theoretical calculations of 13C and 1H NMR and experimental data for the resolution of the savinine structure, and the use of the neural network tool (ANN-PRA) to confirm the structure of the molecule.

scholarly journals Determination of the enol form of asymmetric 1,3-dicarbonyl compounds: 2D HMBC NMR data and DFT calculations

2018 ◽  
Vol 83 (9) ◽  
pp. 953-968
Author(s):  
Meltem Tan ◽  
İshak Bildirici ◽  
Nurettin Mengeş
Keyword(s):  
Experimental Data ◽  
Driving Force ◽  
Theoretical Calculations ◽  
Enol Form ◽  
Dihedral Angles ◽  
Dicarbonyl Compounds ◽  
1H And 13C Nmr ◽  
Nmr Data ◽  
Cdcl3 Solution

In this study, a series of asymmetric aryl 1,3-dicarbonyl compounds were synthesized and their enol forms were observed via experimental data and theoretical calculations. According to the 1H- and 13C-NMR results, all the investigated compounds were found as a single enol form in CDCl3 solution. Moreover, their HMBC spectra were applied to identify the observed enol forms and correlations between certain protons and carbon atoms were considered. The dihedral angles of the asymmetric compounds that have aryl units on both sides were calculated by DFT to understand the reason for the observed enol forms. Small dihedral angles caused longer conjugation, resulting in more stable compounds and it was found that the observed enol forms were based on small dihedral angles, namely, resonance is the driving force. Furthermore, the compounds possessing both aryl and alkyl moieties prefer the enol form towards the aromatic ring side due to longer conjugation.

The conductance behaviour of NaI and NaBPh4 in acetone and in isopropanol at 10, 15, 20, 25, and 30 °C

1989 ◽  
Vol 54 (6) ◽  
pp. 1475-1481 ◽  
Author(s):  
N. Papadopoulos ◽  
G. Ritzoulis
Keyword(s):  
Experimental Data ◽  
Thermodynamic Parameters ◽  
Coulombic Interaction

Molar conductivities at the limit of zero concentration have been evaluated for NaI and NaBPh4 in acetone and in isopropanol at 10, 15, 20, 25, and 30 °C. The experimental data have been analysed by means of the Lee-Wheaton equation. The thermodynamic parameters of the non-coulombic interaction have been evaluated.

scholarly journals Phase Relations in the ZrO2-MgO-FeOx System: Experimental Data and Assessment of Thermodynamic Parameters

2021 ◽  
Author(s):  
Ivan Saenko ◽  
O. Fabrichnaya
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
Solid Solution ◽  
Thermodynamic Parameters ◽  
Spinel Phase ◽  
Experimental Investigations ◽  
X Ray ◽  
Heat Treated ◽  
Preliminary Phase ◽  
Scanning Electron

AbstractThermodynamic parameters were assessed for the MgO–FeOx system and combined with already available descriptions of ZrO2-FeOx and ZrO2-MgO systems to calculate preliminary phase diagrams for planning experimental investigations. Samples of selected compositions were heat treated at 1523, 1673 and 1873 K and characterized using x-ray and scanning electron microscopy combined with energy dispersive x-ray spectroscopy (SEM/EDX). Experiments indicated extension of cubic ZrO2 solid solution into the ternary system at 1873 K (75 mol.% ZrO2, 10 mol.% FeOx and 15 mol.% MgO) and limited solubility of 4 mol.% ZrO2 in spinel phase. Based on the obtained results thermodynamic parameters of C-ZrO2 and spinel phase were optimized.

Privileged hydration sites in aromatic side chains: effect on conformational equilibrium

2017 ◽  
Vol 19 (42) ◽  
pp. 28684-28695 ◽  
Author(s):  
Belén Hernández ◽  
Fernando Pflüger ◽  
Manuel Dauchez ◽  
Mahmoud Ghomi
Keyword(s):  
Conformational Equilibrium ◽  
Theoretical Calculations ◽  
Side Chains ◽  
Aromatic Side Chains

The most energetically favourable hydration sites of aromatic (Phe, Tyr, Trp and His) side chains revealed by DFT-based theoretical calculations.

Cross sections for d-3H neutron interactions with samarium isotopes

2016 ◽  
Vol 104 (8) ◽  
Author(s):  
Junhua Luo ◽  
Chunlei Wu ◽  
Li Jiang ◽  
Long He
Keyword(s):  
Experimental Data ◽  
Neutron Flux ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Nuclear Model ◽  
Activation Technique ◽  
Incident Neutron ◽  
Reaction Threshold ◽  
Talys 1.6 ◽  
The Cross

Abstract:The cross sections for (n,x) reactions on samarium isotopes were measured at (d-T) neutron energies of 13.5 and 14.8 MeV with the activation technique. Samples were activated along with Nb and Al monitor foils to determine the incident neutron flux. Theoretical calculations of excitation functions were performed using the nuclear model codes TALYS-1.6 and EMPIRE-3.2 Malta with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with experimental data found in the literature. At neutron energies 13.5 and 14.8 MeV, the cross sections of the

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